For at least 25 years, municipal wastewater treatment plants have been aware of the need to reduce or eliminate nitrogen compounds from their discharged effluent. Typically, they use a scheme of oxidizing ammonia to nitrate, then convert the nitrate to nitrogen gas. Microbiological processes are usually used for both steps of the process.
Since nitrate compounds are very soluble and mobile in water, they are found naturally only in arid climates. In the United States, though, nitrates are a common contaminant of groundwater in agricultural areas. Run-off from fertilized fields and from locations where animals, such as cattle, pigs and chickens, are raised in high concentration, such as dairy farms and animal feed operations, often contains enough nitrate to affect nearby water wells.
Installations to treat municipal wastes are complex systems. The several types of microorganisms employed to treat ammonia, nitrate, phosphate, and other classes of waste are generally sensitive to their environment, and do not thrive and perform their functions if conditions of Ph, oxidation or reduction potential, nutrient content, and other factors are not within the acceptable range.
Municipal sewage varies widely in these conditions. Sometimes, compounds toxic to microbial life appear suddenly. Sewage treatment plants, thus, must constantly monitor the incoming waste stream and the processes used for treatment. Technicians adjust the process conditions frequently to keep the microbial and other systems running efficiently. Failure to do so can result in release of insufficiently-treated effluent, or shutdown of the plant until the microorganisms are nursed back to health.
Municipal sewage treatment systems are made up of many tanks, covering a few acres of land. The piping, valves, access ports between tanks provide many opportunities for leaks and must be inspected daily, at least. Many of the systems require frequent backflushing and other maintenance of filters.
By comparison, agricultural well water in a given location has a simple composition, which does not fluctuate quickly. The impurities are relatively dilute and readily water-soluble.
Therefore, there has been a need for a simple nitrate removal system for rural agricultural areas that can have optimal operating conditions designed into it. Such a system should be robust, require little adjustment and maintenance, use as little electricity as possible, and be easy to transport to the site and install.